The inner surface of a tubeless pneumatic tire is integrally lined with an air permeation preventive layer (or an inner liner). A butyl rubber exhibiting a better impermeability is used as a material for the air permeation preventive layer. Despite a recent growing demand for light-weight pneumatic tires, the large specific gravity of the butyl rubber has made it difficult to achieve light-weight pneumatic tires. With this taken into consideration, Patent Document 1 has proposed that, instead of the butyl rubber, a thermoplastic resin film with a small specific gravity be used as the air permeation preventive layer, and makes it possible to manufacture light-weight tires.
Unlike the butyl rubber, however, the thermoplastic resin film has no air absorption property. This brings about a problem that, if the air is trapped in the thermoplastic resin film while an uncured tire is made, the trapped air causes blisters on the inner surface of the thermoplastic resin film after the tire is cured.
When a pre-cured green tire is made, first of all, a making drum 20 is covered with a cylindrical thermoplastic resin film 6, as shown in FIG. 5(A). Subsequently, as shown in FIG. 5(B), an uncured rubber sheet member 7 as a tie rubber is wound around the thermoplastic resin film 6 once. Thereafter, the two end portions of the uncured rubber sheet member 7 are spliced together with an overlap, and a step-shaped splice part 11 is thus formed. In this step-shaped splice part 11, as shown in FIG. 6, an air pocket 10 with a triangular cross-section is formed between the uncured rubber sheet member 7 and the thermoplastic resin film 6. After a green tire is made by laminating a carcass layer 5 to the uncured rubber sheet member 7 thus spliced, if the green tire thus made is molded by curing, blisters are caused on the tire because the air pocket 10 is not fully absorbed in the rubber layer. It is likely that the blisters may not only damage the aesthetic appearance of the inner surface of the tire, but also present a cause of breaking the thermoplastic resin film or separating the thermoplastic resin film therefrom while in use.
Particularly in the case of tires of a type in which, like heavy-duty tires, a ratio of carcass lift caused during a curing treatment is large so that carcass cords constituting the carcass layer are likely to bite into the inner liner, a rubber sheet member has to be formed thicker for the purpose of preventing the carcass cords from biting into the inner liner. This presents a problem that the foregoing problem is more likely to occur.    Patent Document 1: Japanese Patent Application Publication No. Hei 8-258506